The present invention relates to a novel method and apparatus for coating plated articles or substrates and to novel articles produced thereby.
One method which has been used for depositing plating material on various articles or substrates is ion vapor deposition which is a vacuum vapor plating process. For example, reference is made to U.S. Pat. No. 4,116,161 which discloses background information concerning ion vapor deposition systems and describes one specific method and apparatus for carrying out the process. The plating material is usually applied to the substrate in order to protect the substrate from its environment and/or to give the substrate an enhanced appearance. For example, aluminum is frequently used to provide a durable and attractive coating for various steel or ferrous metal products.
Although plating material can be deposited as a substantially continuous layer on the substrate via ion vapor deposition, typically, many voids in the plating material do exist. Problems can be encountered in the event electrolyte enters the voids in the plating material since in many environments, the presence of such an electrolyte promotes corrosion. Galvanic corrosion is especially a problem when metals of different electrical potentials such as ferrous metals and aluminum are in contact with each other in the presence of an electrolyte.
It is a primary object of the present invention to provide a novel method and apparatus for coating such plated articles and filling the voids in the plating material in a manner which insures a good bond between the coating and the plating material for minimizing any possibility of galvanic corrosion.
It is a further object of the present invention to provide a novel method in apparatus of the above-described type which is capable of producing novel plated and coated articles in an efficient and economical manner.
When plating materials such as aluminum are applied to a substrate in accordance with prior procedures, the surface of the aluminum plating quickly becomes oxidized upon completion of the plating process and exposed to the atmosphere. The presence of such an aluminum oxide layer at the surface of the aluminum plating material inhibits chemical reaction of the pure metal with various coating materials. Therefore it is a further object of the present invention to provide a novel method and apparatus of the above-described type whereby articles plated with aluminum and the like may subsequently be coated without interference from oxides which previously existed on the surface of the plating material.